Background: Evidence to guide cancer policy-making is scarce in low- and middle-income countries (LMIC). Furthermore, most economic studies in cancer have been conducted from the provider's or payer's perspective. Aim: The ASEAN Costs in Oncology Study (ACTION) was conducted to provide the essential intelligence for national policymakers and official development assistance donors to construct economically sound national cancer control plans. Methods: In the ACTION study, 9513 newly diagnosed cancer patients from eight LMIC in southeast Asia were prospectively followed-up for adverse economic outcomes up to one year after diagnosis, through serial interviews and use of cost diaries. Results: Country-specific analysis of the ACTION Study data had revealed that just within a year of diagnosis, 1 in 2 Malaysian cancer survivors had reported spending more than 30% of their annual household income for cancer related expenditures (FC: financial catastrophe). Strikingly, Malaysia, albeit being a higher income nation, appeared to have fared worse than Thailand, where only 1 in 3 cancer survivors reported FC. Nonetheless, in contrast to finding of the regional study that medical payments (drugs, hospitalization, consultation), largely explained the incidence of FC following cancer, only half of the reported catastrophic expenditures in Malaysia were attributed to medical expenditures suggesting that nonmedical payments related to cancer (e.g., travel, accommodation, childcare) was an important contributor to adverse financial outcomes. Furthermore, marked institutional variations in levels of catastrophic expenditures were observed in Malaysia, even within the public healthcare system. Proportion of patients experiencing FC in the general government hospitals was only 33% compared with 65% in the public academic hospitals. Although late stage at cancer diagnosis largely explained the increased risk of adverse economic outcomes and death, patients from low-income households remained vulnerable even when diagnosed with earlier stages. Conclusion: The findings of the ACTION Study importantly highlight the need for LMIC to undertake their own studies examining the financial impact of cancer in the population, to take affirmative actions to reduce financial loss and premature deaths associated with cancer. From the Malaysian perspective, there appears to be an urgent need to improve social support for cancer in the country, be it through government-led programs such as disability insurance and short term credit or multisectoral collaboration with civil societies, private industries, and philanthropic organizations. Key policy changes should also include prioritization of programs which would allow early detection of cancer, re-examination of the national health financing system to ensure that public funds are channeled to those who need them the most, and addressing disparities in funding between public hospitals.